“Data extrusion” is the general problem in which information is leaked (without authorization), for example by a disgruntled employee, from an organization. A leaked memo, financial forecast, product plan, or technical design could potentially cost a company millions of dollars. Increasingly, security tools such as firewalls and cryptography are configured and used to help prevent electronic data from reaching unauthorized parties. Techniques such as digital watermarking are also employed to help identify the source of information leaked in electronic form.
Unfortunately, these approaches do nothing to mitigate a classic data extrusion technique—printing hardcopies of sensitive information and physically conveying them to an unauthorized party. With little effort, a rogue employee can print memos, schedules, design documents, etc., and slip them into a bag or briefcase without detection. Even if some physical security—such as an exit search—is applied to employees, it is infeasible to evaluate each document carried outside of a typical office building. Moreover, it can be difficult for security personnel to recognize the importance of a particular document. For example, confidential financial data may look comparable to public accounting details.
Therefore, it would be desirable to have a better way to track a printed document to the individual that printed it. It would also be desirable to accomplish such tracking without requiring many, if any, changes to an existing installed base of printers.